1. Carbohydrate the preferred body fuel Page 74
Chapter 5
Carbohydrate the preferred body fuel
Page 74

2. Carbohydrates
Carbohydrates are one of the six essential nutrients and are your body’s main source of energy. They are the sugars, starches, and fiber in your diet.

3. Types of Carbohydrates
Carbohydrates are made of three common chemical elements: carbon, hydrogen, and oxygen. These elements are bonded together to form saccharides, or sugar units.
The arrangement of the elements determines the type of sugar unit formed.
Monosaccharide
Disaccharides
Polysaccharides

4. Monosaccharide
Monosaccharides are carbohydrates composed of single sugar units. (the prefix mono means one)
The three monsacchrides are;
Glucose – sometimes called blood sugar
Fructose – natural fruit sugar, sweetest taste of all sugar
Galactose – always bonded with glucose to make milk sugar

5. Disaccharides
The disaccharides are made up of two sugar units. (the prefix di - means two)
The body splits disaccharides into monosaccharides during digestion.
The disaccharides are;
Sucrose – Table sugar
Maltose – two glucose molecules, formed digesting starch
Lactose – found in milk, one glucose and one galactose. This is the main energy source for breast-fed infants.

6. Polysaccharides
Polysaccharides are carbohydrate that are made up of many sugar units. (the prefix poly means many)
These units are linked in long straight chains or branched chains.
Starch and fiber are both polysaccharides.
Starch is made of many glucose molecules and can be found in grains, potatoes, and legumes.
Fiber is made up of fibrous cell walls of plants. Not digestible without the help of bacteria in the digestive tract. (cellulose, gums, and pectin are types of fiber)

7. The functions of carbohydrates
Carbohydrates serve four key functions;
Provide energy
Spare proteins
Assist in the breakdown of fats
Provide bulk in the diet

8. Produce Energy
Meeting the energy needs of all your cells as they work to sustain life is your body’s main goal. Carbohydrates provide 4 calories of energy per gram. Carbohydrates are the preferred source of energy because your body can use them so efficiently. However if you do not eat enough, your body will draw mainly on protein for tis fuel needs.

9. Spare Proteins
If necessary your body can use protein as an energy source. If you eat too little carbohydrate, your body will use protein for energy and therefore not be able to build and maintain cell structures.

10. Break Down Fats
If the diet is to low in carbohydrates, the body cannot completely break down fats. Incompletely broken down fats form compounds called ketone bodies. These compounds collect in the bloodstream causing it to become more acidic. This acidity can damage cells and organs. Prolonged ketosis can be quite harmful and even deadly.

11. Provide bulk in the diet
Fiber is the carbohydrate responsible for this task. It helps promote normal digestion and elimination of body wastes.
Like the muscles in your arms and legs, the muscles in your digestive tract need a healthy workout. Fiber is the solid material that provides this workout, helping intestinal muscles retain their tone.

12. Other benefits of fiber in the diet
Current interest in fiber stems from observation made by British scientists around They noted that African populations had lower rates of certain GI tract diseases, such as colon cancer, than Western industrialized populations.
Fiber may lower the risks of heart and artery disease. Dietary fiber may reduce the risk of colon cancer and it also helps control diabetes mellitus.

13. Different fibers have different Effects
Fibers vary in their composition and the jobs they perform in the GI tract.
Soluble fiber can dissolve in water and develop a gel-like consistency. These are the fibers that lower blood cholesterol levels. (oat bran, legumes, apples, citrus)
Insoluble fibers don’t dissolve in water and associated with reducing cancer risks. (wheat bran and whole grains)
Both types of fiber has positive health benefits. Many plants contain a combination of both types of fiber so eat a variety of fruits, vegetables and whole grains.

14. How your body uses carbohydrates
All carbohydrates must be in the form of glucose for your cells to use them as an energy source. To get them in this form, your digestive system first breaks down poly- and disaccharides from food into monosaccharides. Monosaccharides are small enough to move across the intestinal wall into the blood. They travel via the blood to the liver. Any fructose and galactose is converted to glucose in the liver.

15. Con’t
When the amount of glucose in the blood rises, which happens when you eat, a hormone called insulin is released from the pancreas. Insulin helps the body lower the blood glucose back to a normal level by triggering body cells to burn glucose for energy. It also causes muscles and the liver to store glucose.
If your cells don’t have an immediate need for glucose, they will store it for later in the form of glycogen.

16. Meeting your carbohydrate needs
May popular foods, including bread, pasta, ice cream, and even baked goods, are rich sources of carbohydrates. Even so, the typical diet falls short of the daily recommended amount of carbohydrate.
Most experts agree that the average diet also has excess simple carbohydrate and not enough complex carbohydrate.

17. Sugars
You can divide sugars in foods into two categories. The first category includes sugars that occur naturally in foods. These sugars include lactose in milk and fructose in fruits. These naturally occurring sugars are generally accompanied by other nutrients and don’t concern experts very much.
The other type of sugar includes sugars that are added to foods at the table or during processing. These sugars are sometimes referred to as refined sugars. These sugars are added to food to make them sweet or to add bulk.

18. Sugar con’t
The main source of sugar in teen diets comes from soft drinks.
Many other foods that are high in added sugar are also high in fat. (candy, cake, cookies, donuts)
Many processed foods such as catsup and cereal are high in added sugar and low in nutrient density.

19. Examples of sugar
Refined sugars
Natural sugars

20. Limiting Sugar
Experts are recommending reducing the amount of refined sugar in the average diet. They are suggesting no more than 25% of your total calories. Based on a 2000 calorie a day diet this would mean no more than 500 calories should come refined sugar.
For reference this would be 125 g of table sugar or 31 teaspoons. About the same amount as is found in 3 or 4 cans of pop.

21. Starches
Starch is the preferred source of fuel for your body. Nutrition experts recommend a minimum of 20 % of your calories come from complex carbohydrates. For a 2000 calorie per day diet that would be 400 calories or about 100 grams of carbohydrate.
Many starchy foods are also excellent sources of vitamins, minerals, and fiber.

22. Fiber
The DRI for fiber is 38 grams per day for males aged 14 through 50. The DRI is grams per day for females aged These recommendations are based on intakes that have been shown to help reduce the risk of heart disease.
You can increase your fiber intake by choosing whole grain products. They contain all three edible parts of the grain kernel.
The bran - fiber
The germ - nutrients
Endosperm - starch

23. Health Questions related to Carbohydrates
Are starchy foods fattening? No, but sometimes the way carbohydrates are served greatly increases the total calories and fat content of the meal. For example, one slice of bread has 12 grams of carbohydrate and 65 calories. Spreading a teaspoon of butter on the bread adds 4 grams of fat and 36 extra calories.
If you are trying to cut calories out of your diet, try cutting the fatty topping rather than the carbohydrates.

24. Questions con’t
Is sugar a hazard to your teeth? There is a clear connection between sweets and tooth decay. Bacteria that live in your mouth feed on the carbohydrates in food particles that are left behind. They form a sticky substance called plaque that clings to teeth. As they grow more they produce acid that weakens tooth enamel. As a result cavities can form.

25. Hyperactivity
Hyperactivity is a condition in which a person seems to be in constant motion and is easily distracted.
Many parents and teachers have observed children are more active after parties and events at which sweet are served.
Researchers have conducted may studies and have found no proof that consuming sweets causes behavior changes.
Children may become excited in the social situation provides and become more active as a result.

26. Hypoglycemia
Hypoglycemia refers to a low blood glucose level. An overproduction of insulin causes blood sugar to drop sharply two to four hours after eating a meal.
The central nervous system requires a constant supply of glucose from the blood. Low blood sugar can cause the physical symptoms of sweating, shaking, headaches, hunger, and anxiety.

27. Lactose intolerance
Lactose intolerance is the inability to digest lactose, the main carbohydrate in milk. This condition is caused by the lack of the digestive enzyme lactase.
People who are lactose intolerant may experience gas, cramping, nausea, and diarrhea when they consume dairy products.